This lets you verify the signature on the model. It won’t help you tell that a decision came from that model. If you want to verify the inference that a model makes, check out https://github.com/zkonduit/ezkl (our project).
> Checking the work takes the same resources as doing the work.
> As much as this would be wonderful in a universe where it's possible, it's simply not possible.
We do live in that universe, under some currently believed assumptions. An NP-complete problem is an example of something where checking a solution is (thought to be) easier than finding one.
Zero-knowledge proofs make it such that checking that a computation (such as inference) has been done correctly is easier than doing the computation (even keeping some parts private). A great reference is here: https://people.cs.georgetown.edu/jthaler/ProofsArgsAndZK.pdf
Our project proves AI model execution with cryptography, but without any trusted hardware (using zero-knowledge proofs): https://github.com/zkonduit/ezkl